My first Publication Agile-Data-Warehouse-Design-eBook | Page 134

Modeling Business Processes
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This sounds a lot like the main clause of the previous order event. The stakeholders
have told you that orders are the reason for shipments. You can find the evidence
for this: the conformed dimension that ties the two events together, by turning
their answer into a how question:
How do you know that a customer ordered the product
for shipment (what data tells you so)?
The answer:
There is an order ID on each shipment.
reveals that the order how detail (ORDER ID [DD]) is effectively a why detail of
shipment, indicating that the two events are likely to be part of a process sequence
with shipments treated as milestones of CUSTOMER ORDERS. You can check
how strict this sequence is by asking, “What about free samples or replacement
products and parts; how are shipments for these processed?” If the answer is, “We
don’t want to consider these when measuring our sales fulfillment processes,” then
perhaps they are events for a marketing or product support data mart, another
sprint, another day. Alternatively, stakeholders might tell you “Pseudo orders are
generated when we ship samples or replacements”. Either way, all the in-scope
shipments are milestone events of orders and ORDER ID is a conformed degener-
ate how/why dimension. Conformed
Figure 4-12 shows the completed shipment event, now named PRODUCT
SHIPMENTS, with its final how detail a SHIPMENT NUMBER degenerate dimen-
sion. The new event name and main clause have also been indented under
CUSTOMER ORDERS to document the process sequence. Note that this sequence,
shipments follow orders and not the reverse, is confirmed by CUSTOMER
ORDERS being an ORDER ID creator (denoted by the * in the ORDER ID
column). CUSTOMER ORDERS must occur first to create the ORDER IDs refer-
enced by PRODUCT SHIPMENTS. Document process
degenerate
dimensions
represent how
details of
process events and
why details of
milestone events
sequences by
indenting milestone
events
Figure 4-12
Adding why and
how dimensions
to shipments